Many industrial and other systems involve the handling and flow control of solid particulate matter. Some such systems involve dispensing of solid particulate material in a batch fashion and thereby involve the opening and closing of valves associated with storage bins or hoppers. Other systems involve processing solid particulates in an essentially continuous fashion. Such systems include catalytic reactor systems or separation processes. In some cases the solid particulates are handled as feedstocks for reactor systems as in the case of synthetic fuel plants that utilize particulate coal as the feedstock material. Other systems such as separation systems involve the handling of particulate solids in a recirculating manner as in the case of particulate adsorbents that are used to purify or separate gas streams.
A problem in the handling and flow control of solid particulate matter is abrasion caused by contact between the solid particulate matter and valve surfaces. This abrasion has two different detrimental effects. First, this abrasion causes excessive valve wear and, especially where valve mating surfaces are involved, causes the valve to fail to function properly. Second, abrasion leads to the crusting and attrition of the particulate solid matter which can cause detrimental excessive dust in the process as well as depletion of particle inventory. Such problems are particularly troublesome in a moving bed adsorption system. Another problem of particle abrasion is that such abrasion causes variations in particle size distribution and this has an undesirable effect on the operation of a fluidized bed system.
It is thus desirable to have a valve for controlling the flow of particulate solid material while enabling reduction in valve wear and in particle abrasion and breakdown.
Often particulate solid material is handled in conjunction with a fluid such as a gas or a liquid. In these situations the abrasion problem discussed above is even more detrimental. This is because although valve wear, which causes the valve to fail to close completely, may not be such as to allow leakage of the solid particulate matter, such valve wear would allow leakage of the fluid matter, necessitating repair or replacement of the valve. A further problem in such systems, which occurs when the valve employs mating surfaces, is the retention of some particulate matter between the mating surfaces. This further complicates the closure problem and allows even further fluid leakage past the valve.
There are systems which handle flow streams of solid particulate matter and a fluid wherein a change in the pressure level of the stream is an important aspect of the system. Such systems may employ lockhoppers and examples of such systems are the introduction of pulverized coal into a pressurized gasifier and the introduction of adsorbent from a low pressure regenerator to a high pressure adsorber for removal of an impurity or component from a gas stream. In these systems the abrasion problem is extremely acute because only very small amounts of wear which cause the valve to fail to achieve pressure-tight closure would be enough to render impossible the proper function of a pressure change system. In these pressurized systems, the problem of particulate retention between valve mating surfaces would render the valve essentially useless to produce a pressure-tight seal.
Accordingly it is an object of this invention to provide an improved valve and method for controlling the flow of particulate solid material while enabling reduction in valve wear and in particle abrasion and breakdown.
It is a further object of this invention to provide an improved valve system and method for controlling the flow of a mixture of particulate solid material and fluid material while enabling reduction in valve wear and in particle abrasion and breakdown to result in enhanced valve system integrity.
It is a still further object of this invention to provide a lockhopper having an improved valve system for controlling the flow of a mixture of particulate solid material and fluid material while enabling reduction in valve wear and in particle abrasion and breakdown to result in enhanced valve system integrity.